1. Field of the Invention
The present invention relates to a radiotherapy system for irradiating a lesion of a human subject with a radiation so as to treat the lesion of the subject.
2. Discussion of the Background
Conventionally, the mainstream of the radiotherapy is toward the so-called a treatment through an external irradiation, that is, treating an internal tumor grown in a human subject with a radiation of an external source. However, this treatment has a fear of adversely affecting any healthy region of the subject. Therefore, the radiotherapy was used as an adjunct way of use, such as treating those remnant, not entirely removed, tumor cells by being exposed to a radiation dose of an external source after the surgical opening of the human body, removal of malignant tumors and the suture of the body parts or radiating the radiation dose directly to the remnant tumor cells before the suture of the body parts involved.
However, a recently developed photon radio-surgery system (PRS) is based on a concept of exposing a region of interest (ROI) in the body of the subject to a radiation dose in a controllable fashion while minimizing an adverse effect on the surrounding healthy region. The PRS comprises a PRS probe 1 and control box 3 as shown in FIG. 1. The PRS probe 1 is comprised of an integral unit of a unique X-ray tube 5 and high voltage power source 7. The unique X-ray tube 5 comprises an electron gun 9, electron accelerator 11, deflection coil 13 and a hollow PRS needle 15. Those electrons generated at the electron gun 9 are accelerated to a required every level, properly deflected, passed through the needle 15 in vacuum and finally strike against a film-like target 17 attached to the inside of the tip of the needle 15, that is, an Au target where an X-ray is emitted.
According to the PRS, it is possible to insert the needle 15 from a skin surface side and to emit a radiation at the inside of the target toward a cavity or space created by the evulsion of malignant tumors tumors in the internal organ or tumors in the brain. Therefore, the irradiation of a healthy region with the radiation can be restricted to the surrounding region of the tumor. In addition, any surgical opening can be eliminated or minimized.
For the treatment using the PRS, the most difficult and attentive care problem is a task of, while uniformly irradiating the tumors with a radiation dose, minimizing the irradiation of the surrounding normal (healthy) region with the radiation. Conventionally, the treatment has been progressed in accordance with planning, such as irradiation position and irradiation time, which are determined under a close treatment planning. And it has not been possible to accurately monitor how a radiation dose distribution may be sequentially developed during irradiation.